[209] | 1 | /* -*- mode: C++; indent-tabs-mode: nil; -*- |
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[7] | 2 | * |
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[209] | 3 | * This file is a part of LEMON, a generic C++ optimization library. |
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[7] | 4 | * |
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[39] | 5 | * Copyright (C) 2003-2008 |
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[7] | 6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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| 7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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| 8 | * |
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| 9 | * Permission to use, modify and distribute this software is granted |
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| 10 | * provided that this copyright notice appears in all copies. For |
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| 11 | * precise terms see the accompanying LICENSE file. |
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| 12 | * |
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| 13 | * This software is provided "AS IS" with no warranty of any kind, |
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| 14 | * express or implied, and with no claim as to its suitability for any |
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| 15 | * purpose. |
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| 16 | * |
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| 17 | */ |
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| 18 | |
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| 19 | #ifndef LEMON_TOLERANCE_H |
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| 20 | #define LEMON_TOLERANCE_H |
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| 21 | |
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| 22 | ///\ingroup misc |
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| 23 | ///\file |
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| 24 | ///\brief A basic tool to handle the anomalies of calculation with |
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| 25 | ///floating point numbers. |
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| 26 | /// |
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| 27 | |
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| 28 | namespace lemon { |
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| 29 | |
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| 30 | /// \addtogroup misc |
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| 31 | /// @{ |
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[209] | 32 | |
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[7] | 33 | ///\brief A class to provide a basic way to |
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| 34 | ///handle the comparison of numbers that are obtained |
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| 35 | ///as a result of a probably inexact computation. |
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| 36 | /// |
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[49] | 37 | ///\ref Tolerance is a class to provide a basic way to |
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[7] | 38 | ///handle the comparison of numbers that are obtained |
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| 39 | ///as a result of a probably inexact computation. |
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| 40 | /// |
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[516] | 41 | ///The general implementation is suitable only if the data type is exact, |
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| 42 | ///like the integer types, otherwise a specialized version must be |
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| 43 | ///implemented. These specialized classes like |
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[72] | 44 | ///Tolerance<double> may offer additional tuning parameters. |
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[7] | 45 | /// |
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| 46 | ///\sa Tolerance<float> |
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| 47 | ///\sa Tolerance<double> |
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| 48 | ///\sa Tolerance<long double> |
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| 49 | |
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| 50 | template<class T> |
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| 51 | class Tolerance |
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| 52 | { |
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| 53 | public: |
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| 54 | typedef T Value; |
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| 55 | |
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| 56 | ///\name Comparisons |
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[49] | 57 | ///The concept is that these bool functions return \c true only if |
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[7] | 58 | ///the related comparisons hold even if some numerical error appeared |
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| 59 | ///during the computations. |
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| 60 | |
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| 61 | ///@{ |
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| 62 | |
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| 63 | ///Returns \c true if \c a is \e surely strictly less than \c b |
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[516] | 64 | static bool less(Value a,Value b) {return a<b;} |
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[7] | 65 | ///Returns \c true if \c a is \e surely different from \c b |
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[516] | 66 | static bool different(Value a,Value b) {return a!=b;} |
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[7] | 67 | ///Returns \c true if \c a is \e surely positive |
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[516] | 68 | static bool positive(Value a) {return static_cast<Value>(0) < a;} |
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[7] | 69 | ///Returns \c true if \c a is \e surely negative |
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[516] | 70 | static bool negative(Value a) {return a < static_cast<Value>(0);} |
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[7] | 71 | ///Returns \c true if \c a is \e surely non-zero |
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[516] | 72 | static bool nonZero(Value a) {return a != static_cast<Value>(0);} |
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[7] | 73 | |
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| 74 | ///@} |
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| 75 | |
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| 76 | ///Returns the zero value. |
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[516] | 77 | static Value zero() {return static_cast<Value>(0);} |
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[7] | 78 | |
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| 79 | // static bool finite(Value a) {} |
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| 80 | // static Value big() {} |
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| 81 | // static Value negativeBig() {} |
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| 82 | }; |
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| 83 | |
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| 84 | |
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[42] | 85 | ///Float specialization of Tolerance. |
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[7] | 86 | |
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[42] | 87 | ///Float specialization of Tolerance. |
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[7] | 88 | ///\sa Tolerance |
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| 89 | ///\relates Tolerance |
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| 90 | template<> |
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| 91 | class Tolerance<float> |
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| 92 | { |
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| 93 | static float def_epsilon; |
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| 94 | float _epsilon; |
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| 95 | public: |
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| 96 | ///\e |
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| 97 | typedef float Value; |
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| 98 | |
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| 99 | ///Constructor setting the epsilon tolerance to the default value. |
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| 100 | Tolerance() : _epsilon(def_epsilon) {} |
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[49] | 101 | ///Constructor setting the epsilon tolerance to the given value. |
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[7] | 102 | Tolerance(float e) : _epsilon(e) {} |
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| 103 | |
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[49] | 104 | ///Returns the epsilon value. |
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[7] | 105 | Value epsilon() const {return _epsilon;} |
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[49] | 106 | ///Sets the epsilon value. |
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[7] | 107 | void epsilon(Value e) {_epsilon=e;} |
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| 108 | |
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[49] | 109 | ///Returns the default epsilon value. |
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[7] | 110 | static Value defaultEpsilon() {return def_epsilon;} |
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[49] | 111 | ///Sets the default epsilon value. |
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[7] | 112 | static void defaultEpsilon(Value e) {def_epsilon=e;} |
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| 113 | |
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| 114 | ///\name Comparisons |
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[72] | 115 | ///See \ref lemon::Tolerance "Tolerance" for more details. |
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[7] | 116 | |
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| 117 | ///@{ |
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| 118 | |
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| 119 | ///Returns \c true if \c a is \e surely strictly less than \c b |
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| 120 | bool less(Value a,Value b) const {return a+_epsilon<b;} |
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| 121 | ///Returns \c true if \c a is \e surely different from \c b |
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| 122 | bool different(Value a,Value b) const { return less(a,b)||less(b,a); } |
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| 123 | ///Returns \c true if \c a is \e surely positive |
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| 124 | bool positive(Value a) const { return _epsilon<a; } |
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| 125 | ///Returns \c true if \c a is \e surely negative |
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| 126 | bool negative(Value a) const { return -_epsilon>a; } |
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| 127 | ///Returns \c true if \c a is \e surely non-zero |
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[16] | 128 | bool nonZero(Value a) const { return positive(a)||negative(a); } |
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[7] | 129 | |
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| 130 | ///@} |
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| 131 | |
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| 132 | ///Returns zero |
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| 133 | static Value zero() {return 0;} |
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| 134 | }; |
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| 135 | |
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[42] | 136 | ///Double specialization of Tolerance. |
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[7] | 137 | |
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[42] | 138 | ///Double specialization of Tolerance. |
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[7] | 139 | ///\sa Tolerance |
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| 140 | ///\relates Tolerance |
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| 141 | template<> |
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| 142 | class Tolerance<double> |
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| 143 | { |
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| 144 | static double def_epsilon; |
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| 145 | double _epsilon; |
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| 146 | public: |
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| 147 | ///\e |
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| 148 | typedef double Value; |
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| 149 | |
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| 150 | ///Constructor setting the epsilon tolerance to the default value. |
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| 151 | Tolerance() : _epsilon(def_epsilon) {} |
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[49] | 152 | ///Constructor setting the epsilon tolerance to the given value. |
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[7] | 153 | Tolerance(double e) : _epsilon(e) {} |
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| 154 | |
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[49] | 155 | ///Returns the epsilon value. |
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[7] | 156 | Value epsilon() const {return _epsilon;} |
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[49] | 157 | ///Sets the epsilon value. |
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[7] | 158 | void epsilon(Value e) {_epsilon=e;} |
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| 159 | |
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[49] | 160 | ///Returns the default epsilon value. |
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[7] | 161 | static Value defaultEpsilon() {return def_epsilon;} |
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[49] | 162 | ///Sets the default epsilon value. |
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[7] | 163 | static void defaultEpsilon(Value e) {def_epsilon=e;} |
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| 164 | |
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| 165 | ///\name Comparisons |
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[72] | 166 | ///See \ref lemon::Tolerance "Tolerance" for more details. |
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[7] | 167 | |
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| 168 | ///@{ |
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| 169 | |
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| 170 | ///Returns \c true if \c a is \e surely strictly less than \c b |
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| 171 | bool less(Value a,Value b) const {return a+_epsilon<b;} |
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| 172 | ///Returns \c true if \c a is \e surely different from \c b |
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| 173 | bool different(Value a,Value b) const { return less(a,b)||less(b,a); } |
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| 174 | ///Returns \c true if \c a is \e surely positive |
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| 175 | bool positive(Value a) const { return _epsilon<a; } |
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| 176 | ///Returns \c true if \c a is \e surely negative |
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| 177 | bool negative(Value a) const { return -_epsilon>a; } |
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| 178 | ///Returns \c true if \c a is \e surely non-zero |
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[16] | 179 | bool nonZero(Value a) const { return positive(a)||negative(a); } |
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[7] | 180 | |
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| 181 | ///@} |
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| 182 | |
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| 183 | ///Returns zero |
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| 184 | static Value zero() {return 0;} |
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| 185 | }; |
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| 186 | |
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[42] | 187 | ///Long double specialization of Tolerance. |
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[7] | 188 | |
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[42] | 189 | ///Long double specialization of Tolerance. |
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[7] | 190 | ///\sa Tolerance |
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| 191 | ///\relates Tolerance |
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| 192 | template<> |
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| 193 | class Tolerance<long double> |
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| 194 | { |
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| 195 | static long double def_epsilon; |
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| 196 | long double _epsilon; |
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| 197 | public: |
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| 198 | ///\e |
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| 199 | typedef long double Value; |
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| 200 | |
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| 201 | ///Constructor setting the epsilon tolerance to the default value. |
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| 202 | Tolerance() : _epsilon(def_epsilon) {} |
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[49] | 203 | ///Constructor setting the epsilon tolerance to the given value. |
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[7] | 204 | Tolerance(long double e) : _epsilon(e) {} |
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| 205 | |
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[49] | 206 | ///Returns the epsilon value. |
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[7] | 207 | Value epsilon() const {return _epsilon;} |
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[49] | 208 | ///Sets the epsilon value. |
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[7] | 209 | void epsilon(Value e) {_epsilon=e;} |
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| 210 | |
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[49] | 211 | ///Returns the default epsilon value. |
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[7] | 212 | static Value defaultEpsilon() {return def_epsilon;} |
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[49] | 213 | ///Sets the default epsilon value. |
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[7] | 214 | static void defaultEpsilon(Value e) {def_epsilon=e;} |
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| 215 | |
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| 216 | ///\name Comparisons |
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[72] | 217 | ///See \ref lemon::Tolerance "Tolerance" for more details. |
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[7] | 218 | |
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| 219 | ///@{ |
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| 220 | |
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| 221 | ///Returns \c true if \c a is \e surely strictly less than \c b |
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| 222 | bool less(Value a,Value b) const {return a+_epsilon<b;} |
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| 223 | ///Returns \c true if \c a is \e surely different from \c b |
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| 224 | bool different(Value a,Value b) const { return less(a,b)||less(b,a); } |
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| 225 | ///Returns \c true if \c a is \e surely positive |
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| 226 | bool positive(Value a) const { return _epsilon<a; } |
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| 227 | ///Returns \c true if \c a is \e surely negative |
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| 228 | bool negative(Value a) const { return -_epsilon>a; } |
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| 229 | ///Returns \c true if \c a is \e surely non-zero |
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[16] | 230 | bool nonZero(Value a) const { return positive(a)||negative(a); } |
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[7] | 231 | |
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| 232 | ///@} |
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| 233 | |
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| 234 | ///Returns zero |
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| 235 | static Value zero() {return 0;} |
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| 236 | }; |
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| 237 | |
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| 238 | /// @} |
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| 239 | |
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| 240 | } //namespace lemon |
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| 241 | |
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| 242 | #endif //LEMON_TOLERANCE_H |
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